<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <button class="btn">更换</button>
    <button class='btn1'>点击修改box的样式</button>
    <div>
        <img src="../image/logo1.png" alt="" class="pic" title="logo图标">
    </div>
    <div class="box">box</div>
    <script src="../js/demo4.js"></script>
</body>

</html>